Prodecologia developed a sorting machine based on Specim technology that achieves 98% polymer purity. Specim’s hyperspectral imaging was used to create Prodecologia’s near-infrared (NIR) separator, a tool that identifies, sorts, and separates different types of polymers — resulting in a more efficient and effective polymer recycling process.

Processing polymer waste into reusable materials for the secondary market

The environmental impact of polymer waste has become a pressing sociological issue in recent years. “Polymer waste is a worldwide ecological problem that should be addressed by using polymer recycling,” says Andrii Honchar, chief technologist of Prodecologia. “Instead of relying upon landfill disposals, we should place focus on converting polymer waste into reusable materials.”

The incentive for using secondary polymers has been driven primarily by heightened environmental concerns and the public’s demand for increased eco-responsibility. However, recycling is also economically feasible and energy efficient. Processing polymer waste into new usable materials for the secondary market requires only half the overall energy expenditure compared to primary polymer production. After performing an in-depth analysis, Prodecologia developed a polymer recycling technology that would increase efficiency and limit environmental waste.

Prodecologia was originally founded in Eastern Europe as a company focused on designing, manufacturing, and supplying magnetic separators, metal detectors, and electrostatic separators. Although Prodecologia had previously recycled cable waste, printed circuit boards, and various other materials, polymer pressing was widely considered a complex new process. After meeting various challenges, Prodecologia is now focused on creating sustainable technologies that effectively process and recycle polymer waste products.

Figure 1: Prodecologia’s NIR separator. Separation of PET, PVC, PE, PP and other plastics.
Capacity 600-700 kg/h for PP + PE mix and 500-600 kg/h for PET-flakes. Width of the working area 1200 mm.

Challenges of polymer processing

Prodecologia decided to develop and implement new complex polymer processing solutions to meet the diverse needs of its customers. But developing the technologies came with several challenges, including that recyclable polymers come in various shapes, sizes, and purity scores. “The ability to efficiently process the maximum number of variant inputs and raw materials is the main criteria by which polymer technology is evaluated,” Honchar says.
Prodecologia aimed to implement complex technical solutions that would result in polymer purity scores greater than 98%. The first step in the process was performing the electrostatic separation of polymers based on the well-known phenomenon of the triboelectric effect, which involves creating an electrostatic field and charging polymers of opposite polarity with one another.

Although electrostatic technology is effective when working with relatively simple products, it can be difficult to obtain final polymer concentrates with high purity scores of over 95%. Sorting polymer mixtures using this technology does not allow for the flexibility of changing input products or types of polymer materials. These technological limitations would allow for purity scores nearing 95%, but customers often need polymer mixtures with purity ratings above 98%. Prodecologia also faced tough marketplace competition from other companies in the European and Chinese polymer recycling markets.

Using hyperspectral imaging to improve polymer sorting

Prodecologia set out to produce sustainable polymer recycling technology that could readily compete in the international recycling market. To satisfy customer requirements, the goal was to achieve a polymer concentration of greater than 98% purity.

The company determined that hyperspectral imaging technology was viable solution for effectively sorting, processing, and recycling polymer waste products. By combining imaging and spectroscopy, hyperspectral imaging offers many advantages over traditional systems based on X-ray, RGB, or multispectral sensors. Line-scan hyperspectral camera is an effective inspection tool that can locate, sort, and quantify the concentration of various materials invisible to common cameras or the human eye.

Many problems previously identified could be solved using hyperspectral imaging in the near-infrared (NIR) region. The NIR spectra allow accurate and reliable classification of different types of polymers (PP, PE, PS, ABS, PET, PVC, and PC) found in household and industrial waste.

When operating in the NIR spectral range, hyperspectral imaging can identify and sort various types of polymeric materials inline quickly and effectively with a single scan, increasing the purity of recycled material (more than 98%) and limiting waste byproducts.

Figure 2: Two Specim FX17 hyperspectral cameras inspect the material stream and identify different types of polymers in real-time.

Figure 3: Real-time hyperspectral scanning identifies different types of polymers. Pink stands for PE and blue for PP.

Developing and implementing the NIR separator

When initially developing the first laboratory NIR separator, Prodecologia consulted with various spectral camera manufacturers but determined that most companies would not be able to fully satisfy the stringent technical conditions required for the implementation of the industrial project. The company identified Specim as a camera and software manufacturer that could meet the complexities of the project.

“Specim is a viable supplier of hyperspectral vision technology with a history of industry experience,” Honchar says. “With a vast range of products, companies can choose and utilize the technology that best suits the needs and goals of their organization. ”

The NIR separator operates by first identifying various types of polymers within each particle of a mixture. The particles are then extracted, separated using a high-speed pneumatic system. Hyperspectral imaging (HSI) speeds up the process by quickly and effectively analyzing the chemical composition of plastic resin. To maximize the efficiency of the polymer processing and purity of recycled material, Prodecologia selected the Specim FX17 NIR HSI camera due to its high resolution and high frame-rate capabilities.

The main components of the NIR separator include:

  • The Specim FX17 NIR hyperspectral camera that forms HSIs of each particle
  • A microprocessor unit that identifies and creates RGB models of each mixture
  • Pneumatic systems for ejection needed type of polymer

Figure 4: Air ejectors shooting off the rejected material.

SpecimONE sped up development

Prodecologia utilized Specim’s spectral imaging platform SpecimONE to develop the polymer sorting application for its NIR separator. The SpecimONE comprises:

  • Specim FX camera: an industrial-proven HSI camera
  • SpecimINSIGHT: an HSI data-analyzing software tool
  • SpecimCUBE: a data-processing platform

The SpecimINSIGHT software allowed Prodecologia’s data analysts to efficiently analyze the hyperspectral data gathered from the Specim HSI camera offline and create and validate the classification models to identify different types of polymers. The classification models created with SpecimINSIGHT were then run with the SpecimCUBE, which transferred the data to the inline system to sort the different plastic types in real time.

Prodecologia was able to significantly fasten the development of the NIR separator with the SpecimONE platform. “The implementation of the NIR separator with the Specim’s hardware and software solutions only took six months, which was a vast improvement compared to other systems that were stuck in development for several years and never reached full completion,” says Honchar.

Figure 5: Separation result. Rejected PP on the left and PE with concentrate purity up to 98% on the right.

Towards the next challenge: Black plastics recycling

Using environmentally sustainable and economically viable methods, the NIR sorting technology has helped Prodecologia resolve challenges previously faced within the polymer recycling market. Hyperspectral imaging in the NIR region was an effective tool for obtaining high-quality polymer concentrates. Using this technology, Prodecologia can now sort multicomponent polymer mixtures by type. Specim’s NIR hyperspectral cameras are well integrated into Prodecologia’s NIR separator, creating a synergistic solution to efficient industrial polymer recycling.

Prodecologia’s next objective involves the recycling of black polymers. Black plastic comprises a significant part of household and industrial waste. A majority of this ends up in landfills because optical sorting systems have difficulty recognizing it. This is widely considered a challenging undertaking, but Prodecologia is confident that the Specim FX50 MWIR (mid-wave infrared) hyperspectral camera can efficiently handle the recycling of black polymers due to its 2.7–5.3 μm spectral range required for sorting black plastics. Prodecologia believes that systems capable of recovering black plastics from the waste stream will have vast financial and environmental implications in the polymer waste processing industry in the future.

Figure 6: Specim FX17 camera works in a line-scan mode, and collects hyperspectral data in the near-infrared NIR region (900 to 1700 nm).

Figure 7: SpecimINSIGHT software allows users to explore hyperspectral data and create and classification models.

Figure 8: SpecimCUBE processing platform runs the classification models created by SpecimINSIGHT in realtime.

Watch the videos to learn more about the Prodecologia’s NIR separator:

NIR separator – receiving of PE concentrate

NIR separator – receiving of PET concentrate